Abrasive gun



PAASCHE Oct. 1 9

ABRASIVE GUN 2 Sheet 1 Filed s p 1946 Oct. 17, .1950 J. A. .PAASCHE 2,526,403

' ABRASIVE GUN I Filed Sept. 5', 1946 2 Sheets-Sheet 2 Patented Oct. 17, 1950 UNITED STATES PATENT OFFICE ABRASIVE GUN Jens A. Paasche, Chicago, Ill.

Application September 5, 1946, Serial No. 694,954

Claims.

The present invention relates in general to abrasive guns, wherein abrasive is supplied to a stream of compressed air which propels the abrasive through an orifice to impinge on working surface; and in particular to an improved light abrasive gun for cutting or etching insig ia or ornamental designson articles made of glass, plastic, metal or other materials, and for honing, surfacing, or burring small parts.

One of the objects of the invention is to provide an abrasive gun of the type described wherein the number of parts which are exposed to the air stream carrying abrasive is-reduced to an absolute minimum to prolong the life of the gun and to facilitate rapid and economical replacement of such parts when they become worn to an extent suificient to interfere with proper operation of the gun.

A further object of the invention is to provide an abrasive gun of the type described which is arranged to be held like a pistol in order t promote accurate direction of the air stream carrying abrasive over a portion of a working surface which is to be etched or out.

Another object of the invention is to provide an abrasive gun of the type described which is constructed so as to permit ready adjustment of the air stream and the rate at which abrasive is fed thereto, and which may be recharged with abrasive without interfering with any of the adjustments of the gun.

Still another object of the invention is to provide an abrasive gun of the type described wherein the abrasive is fed to the gun by gravity, rather than by the use of a pressure feed, to prolong I the life of the gun and to simplify the construction and operation thereof.

A still further object of the invention is to provide an abrasive gun of the type described which is very rugged and durable, and yet is economical to manufacture.

These and other objects of the invention will be more fully understood upon a perusal of the specification taken in conjunction with the accompanying drawings, wherein:

Fig. l is a side elevational view of an abrasive gun constructed in accordance with the present invention; r

Fig. 2 is an enlarged cross sectional view of the abrasive gun shown;

Fig. 3 is a transverse sectional view of the gun taken along the line 33 of Fig. 1; and

Fig. 4 is a perspective view of the gun and overhead abrasive container which may be used there- .with.-

Described briefly, the abrasive gun of the present invention comprises a barrel portion provided with a pistol grip handle and with a trigger for operating a valve built into the barrel portion of the gun to control the flow of air from a source of compressed air connected to the gun when it is in use. When the trigger is in the operative position, compressedair is allowed to flow through the barrel portion of the gun and travels through a pair of axially aligned tubes having a gap of adjustable width between their adjacent ends. A container for abrasive is connected with the muzzle end of the barrel portion, which is provided with a passage for conveying abrasive from the container to the gap between the tubes through which the compressed air passes. Particles of abrasive are drawn through the gap between the tubes of venturi action and are propelled through the last tube by the air stream to impinge on a working surface.

Referring now t Figs. 1 to 3 of the drawings, the barrel portion, indicated generally at 4, consists principally of a central body portion 6 at one end of which there is attached a valve casing 8 and at the other end of which there is attached an abrasive feeder portion ID. A pistol grip handle I2 is secured to the body portion 6 of the barrel by means of a screw 14 passing through a counter-bored opening in the handle [2 and threaded into a tapped plug [5 having grooves milled therein which fit around the sides of a slot in the body portion 6. A trigger I6, having a U-shaped cross section, is pivoted at its upper end on a pin 18 which passes through clearance holes in the trigger l6 and is threaded into the body portion 6. A link 20 is pivotally secured at one end to the trigger [6, by means of a pin 22 passing therethrough, and is coupled to a plunger 24 at its other end. The plunger 24 passes through an axial opening in a cylindrical member 26 provided with a flange which is clamped between the body portion 6 and the valve casing 8.

Valve casing 8 includes a seat 28 against which a valve head 30 is biased by means of a compression spring 32 extending between the valve head 30 and a hollow nut 34 which is threaded in the valve casing 8. One end of plunger 24 enters a recess in the valve head 30 whereby operation of the trigger I6 moves the valve head 30 in opposition to the compressional force of the spring 32 to open the valve. The valve casing 8 is provided with suitable threads to permit an air hose to be coupled thereto. When the valve is open air is enabled to pass from the air hose (not shown) coupled to the valve casing 8 through the hollow nut 34, between the valve head 30 and the valve seat 28, between a shank portion of the cylindrical member 26 and the valve casing 8, thence through an opening 36 in the cylindrical member 26 to a tube 38 extending through the central body portion 6. An adjustable knurled stop screw 49 is threaded into a tapped opening in the handle 12 to limit the stroke of trigger i6 and thus limit the motion of the valve head 30. A compression spring 42 maintains tension on the stop screw 4%] to prevent undesired movement thereof.

The forward end of body portion 6 is coneshaped and matches in contour the feeder portion H! which is secured thereto by a flanged nut 44 threaded on the feeder portion 10 and engaging a split ring is disposed in an annular recess in the body portion 6. The tube 33 extending through the body portion terminates in a central opening in the forward end of the body portion 6 and is sealed thereto by 'means of a gasket 48.

The feeder portion it is provided with a counter-bored axial opening through which ther extends a flanged tube 58, which is preferably formed of hardened steel. The axial opening in the feeder portion It is enlarged at the forward end thereof and communicates with a hollow stem 52 extending from the feeder portion it. A cylindrical container as is threaded on the stem 52. The container 54 may be left open at the upper end to permit rapid recharging with abrasive, or maybe provided with a removable cover if desired. When abrasive is placed in the container 54 it fills the stem 52 and surrounds the tube 5!! extending axially through the feeder portion ll] of the gun.

A cap member '56 is threaded over the open end of feeder member is and is provided with a tapped axial opening in which the'rei'sthread'ed a tip or tube '58. The tip 58 has an axial opening therein which is countersunk at the end "adj aoent the tip of tube '50, which is chamfered to match the contour "of the conical portion of the tip. 'The tip'58 is preferably provided with a hardened steel liner iii) to facilitate manufacture thereof, but the entire tip may be formed of hardened steel if desired. A lock nut 62 is threaded on the tip 58 and serves to prevent relative movement between the tip "58 and the cap member 56 afterthe tip 58 has been adjusted to provide the desired gap, -or annular passage, between the conical end thereof and the end of tube 56.

When the gun is being used, the operation of trigger it enables compressed air to how through tubes 38 and 50, and thence through the tip 58.

The diameter of the opening in tip 53 is preferably made larger than the inner diameter of the tube 50, whereby air is drawn through the abrasive in the container 54 and in stem 52 through the gap between the tip of tube 59 and tip member 58. Particles of abrasive, which may be aluminum oxide, silicon carbide, or the like, will thus be carried through the gap into the air stream issuing from tip 58. The rate at which the abrasive is fed to the air stream may be reg-ulated by loosening lock nut '52 and rotating the tip 58 to either increase' or decrease the gap-be tween the tip 58 and the tube 50. This adjustment enables a continuous variationfrom afine spray of abrasive, suitable for detail work, to a strong blast of abrasive, suitable forcoarse work, to be obtained.

It will be noted that the only portion of the "gun that is subjected to abrasive actionfs the tip 58. which is provided with a hardened steel liner or sleeve, or is formed entirely of hardened steel, to preclude rapid wearing thereof, and which in any event may be replaced very readily.

In instances where the gun is used continuously, it may be undesirable to have the abrasive container mounted on the gun since the capacity of such a container is necessarily limited. In such cases a larger overhead container may be coupled to the gun, as has been illustrated in Fig. 4. The container 64 is provided with a handle 66 to enable it to be suspended from any convenient overhead support. A flexible hose '68 is connected between the container 64 and the stem 52 extending from the abrasive feeder portion 10 'of the gun. It will be noted that, as may best be seen in Fig. 2, the angle at which the stem 52 projects from the gun may readily be adjusted by loosening the nut 44 and rotating the feeder portion Iii relative to the body portion 6.

The cone-shaped surfaces of these parts insures ."a tightsealin any relative angular position when the .nut 44 is retightened. The hose 68 may thus be extended away from the gun in any desired direction toiprovide clear Vision and to permit free use of the gun.

It should now be apparent that by reason of the novel construction of the abrasive gun described herein a very convenient means for performing delicate cutting'or'etching operations in a rapid manner has been provided. The construction is such as to enable the gun to withstand continuous rough usage, to enable rapid replacement of the abrasive without disturbing the ad- F .ju'stment of the gun, and to promote accurate direction of theair stream carrying abrasive over a surface. which is to be etched or abrasive blasted. The gun is particularly suited for use as an etching tool for making directory panels, signs and name plates; and for applying stenciled designs to articles made. of glass, plastic, stone,

metal, or other materials; but may also be used for other delicate operations, such as honing, surfacing, and burring of fine instrument parts.

While a particular "embodiment of the invention has been shown by way of illustration, it

should be apparent that various modifications may be madetherein without departing from the invention .in.it's broader aspects, and therefore it is the aim. in the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.

Having thus described the invention, What is claimed as new and desired to be Secured by .Letters Patent is:

1. An abrasive gun comprising a hollow body portion. a tubular member threaded into said body portion, a tube disposed in said body portion in "axial alignment with and slightly spaced from said member -'to provide an annular passage, means positioned above said body portion to permit gravity feeding of abrasive "to the interior member during operation of the gun, and means for locking said'memb'erin anyselected position. -2. In an abra'sive gun, a hollow body portion, a

"tubular memberthreaded into said body portion,

a tube disposed'in said body portion in axial alignment with and slightly spaced from said tubular member to provide an annular passage, means for feeding abrasive material around said tube and through said annular passage, means for directing compressed air through said tube and said tubular member, rotation of said tubular member in said body portion serving to vary the size of said annular passage between said tube and said tubular member whereby to regulate the rate at which material is supplied to the air stream which issues from said tubular member during operation of the abrasive gun, and means for locking said tubular member in any selected position. 7

3. In an abrasive gun as set 'forth in claim 2,,

a structure wherein the tubular member is provided with a wear resistant lining.

4. In an abrasive gun, a hollow body portion, a. cap threadedly connected to one end of said body portion and having a threaded aperture formed therein, a nozzle memzber threadedly connecting with said threaded aperture, a tube disposed in said body portion in axial alignment with and slightly spaced from said nozzle member to provide an annular passage therebetween, means for feeding abrasive material to the interior of said body portion and around said tube, means for directing compressed air through said tube and said nozzle member, the size of said annular passage being adjustable upon rota- 5. An abrasive gun comprising a hollow body portion having an aperture therein, a tube in said body portion disposed in axial alignment with said aperture and slightly spaced from the Wall of the body portion defining the aperture, the cross sectional area of the passage definedbetween said body portion and said tube being substantially greater than the passage defined by the end of said tube and the wall of the aperture in said body portion, a container for abrasive positioned above said body portion and mounted thereon and communicating with the interior thereof so as to permit gravity feeding of abrasive to the passage between said tube and said body portion and storage of abrasive in said last named passage around said tube, and means for directing compressed air through said tube and said aperture, whereby particles of abrasive are drawn through the space between said tube and the wall of the body portion defining the aperture and are propelled through the aperture to impinge on a working surface during operation of the gun.

JENS A. PAASCHE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 839,433 Kelly Dec. 25, 1906 992,144 Babcock May 16, 1911 1,073,149 Lawrence Sept. 16, 1913 2,133,149 Poncelet Oct. 11, 1938 2,305,976 McKnight Dec. 22, 1942 

